(1) Field of the Invention
This invention generally relates to a rewriteable optical disc, an optical disc recording apparatus, an optical disc recording method, and a storage medium for storing an optical disc recording program, and specifically to a rewriteable optical disc, an optical disc recording apparatus, and an optical disc recording method for facilitating dubbing, and a storage medium for storing an optical disc recording program for facilitating dubbing.
(2) Description of the Prior Art
Recently, DVD(Digital Video/Versatile Disc)-RAM, one of rewriteable optical discs, has been commercialized. The DVD-RAM is a phase-change-type disc having a capacity of several giga bytes. Now that MPEG and MPEG2, standards for compressing/encoding AV (Audio Visual) data, have gone into practical use, it is expected that the DVD-RAM will be used not only in computers but as an AV recording/reproducing medium. That is, the widespread expectation is that the DVD-RAM will be prevalent and replace the magnetic tape which has been a major AV recording/reproducing medium.
It is possible for users to record data onto DVD-RAMs while this is not possible with read-only DVDs (hereinafter referred to as DVD-ROMs). As a result, it is expected that DVD-RAMs provide a wide range of uses.
However, it is not so easy to perform dubbing on conventional optical discs as on the magnetic tapes.
The magnetic tapes have independent areas for recording video tracks and audio tracks. Also, video data and audio data are read/written from/onto the magnetic tapes via respectively independent magnetic heads. Accordingly, it is very easy to perform dubbing of audio data on the magnetic tapes. In case of analog video tape recorders, the time (delay) taken for starting reproducing audio or video data read from the magnetic tape via the head is nearly zero. This is the same for the time (delay) taken for starting writing input audio or video data onto the magnetic tape via the head. As a result, data can be recorded onto the magnetic tape at the same time as the data having been recorded on the magnetic tape is reproduced.
In contrast, in case of an optical disc, the video stream and audio stream are multiplexed into one MPEG stream to be recorded onto the disc. Also, only one pickup is used for both reading and writing data from/onto the optical disc. In the MPEG stream, the video stream is placed before and is processed earlier than the audio stream. This is because the amount of video data to be decoded is greater than that of audio data. Such data structure of the MPEG stream and the construction of the recording/reproducing apparatus make it difficult to perform dubbing to record dubbed data onto the optical disc.
It is therefore an object of the present invention to provide an optical disc which allows the dubbing to be performed as easily as magnetic tape medium, and an optical disc recording apparatus, an optical disc reproducing apparatus, and a program storage medium storing a program executed in the optical disc recording apparatus.
The above object is fulfilled by a recordable optical disc comprising: a data area in which one or more video objects are recorded, where a video stream, a first audio stream, and a second audio stream are multiplexed into the one or more video objects, the second audio stream being used for dubbing.
With the above-stated construction, it is possible to perform dubbing easily since the second audio stream for dubbing is recorded beforehand in the video objects. It is also possible to record the dubbing audio data together with the original audio data (the first audio stream) since the first and second audio streams are separately recorded.
As a result, it is possible to achieve new applications (e.g., applications for practicing pronunciation of some language and applications including dubbings for Karaoke) which have not been achieved conventionally in recordable optical discs. It is also possible to repeatedly record the dubbing while maintaining the original audio data.
In the above recordable optical disc, the second audio stream for dubbing may have the same reproduction time period as that of the first audio stream.
With such a construction, it is possible to ensure that the first audio stream is dubbed onto the second audio stream over the entire reproduction period.
In the above recordable optical disc, the second audio stream for dubbing may be recorded with the same bit rate as the first audio stream.
With such a construction, it is possible to ensure that the second audio stream for dubbing has the same audio quality as the first audio stream. This is achieved, for example, by using the same encoding mode and the same sampling frequency for the second audio stream as the first audio stream.
In the above recordable optical disc, the second audio stream for dubbing may include audio data which has been generated from the same source as the first audio stream.
With such a construction, the second audio stream for dubbing has the same source as the first audio stream. This enables the audio stream to be used for the performance of a partial dubbing. Furthermore, the second audio stream having had partial dubbing performed includes the same audio data as the first audio stream in a part other than the part in which the dubbing data is recorded. Therefore, the reproducing apparatus needs not switch between the first and second audio streams during the reproduction.
In the above recordable optical disc, the first audio stream may include a plurality of packs which each have a predetermined size, and the second audio stream may include a plurality of packs respectively corresponding to the plurality of packs included in the first audio stream.
Also, in the above recordable optical disc, each of the plurality of packs in the second audio stream may include the same audio data as that included in a corresponding one of the plurality of packs in the first audio stream.
With such a construction, the second audio stream for dubbing corresponds to the first audio stream in units of packs and has the same audio data. As a result, in addition to the above-described partial dubbing, it is possible to return the second audio stream to the state before dubbing. This is achieved by copying the audio data of packs of the first audio stream to the corresponding packs of the second audio stream.
The above recordable optical disc may further comprise: a management area for storing one or more pieces of management information which respectively correspond to the one or more video objects, each of the one or more pieces of management information shows a state of the second audio stream in a corresponding video object and indicates whether dubbing has been performed on the second audio stream in the corresponding video object.
With the above construction, it is possible for the recording apparatus and the reproducing apparatus to manage whether the dubbing stream has had dubbing performed by referring to the management information.
In the above recordable optical disc, each of the one or more pieces of management information may further indicate one of a first state, a second state, and a third state, where the first state indicates that the second audio stream includes the same audio data as the first audio stream, the second state indicates that the second audio stream includes audio data which has been generated from the same source as the first audio stream, and the third state indicates that audio data of the second audio stream is irrelevant to audio data of the first audio stream.
With such a construction, it is possible for the recording apparatus and the reproducing apparatus to manage the state of the dubbing stream by referring to the management information.
The above object is also fulfilled by a recordable optical disc comprising: a data area in which one or more video objects are recorded, where a plurality of elementary streams are multiplexed into the one or more video objects, where one of the plurality of elementary streams is a video stream and another one is a dubbing stream which is used for dubbing either of audio data and sub-picture data; and a management area for storing one or more pieces of management information which respectively correspond to the one or more video objects, each of the one or more pieces of management information shows a state of the dubbing stream in a corresponding video object.
With the above construction, the dubbing stream is multiplexed into the video objects beforehand, and an area is secured in the dubbing stream so that either audio data or sub-picture data is recorded in the area. This facilitates the dubbing. Furthermore, it is possible for the recording apparatus and the reproducing apparatus to manage whether the dubbing stream has had dubbing performed by referring to the management information.
In the above recordable optical disc, the dubbing stream may be used for dubbing the sub-picture data representing one or more still pictures, each of the one or more video objects includes a plurality of video object units, and each of the plurality of video object units includes a part of the video stream corresponding to a predetermined reproduction time period and includes a part of the dubbing stream which is to be reproduced together with the part of the video stream, where the part of the dubbing stream corresponds to at least one still picture, and each of the one or more pieces of management information indicates whether dubbing has been performed on the dubbing stream in the corresponding video object.
Also, in the above recordable optical disc, the part of the dubbing stream included in each video object unit may correspond to a still picture having a predetermined size.
With the above construction, it is possible to easily dub at least one still picture into each video object unit.
The above object is also fulfilled by an optical disc recording apparatus for recording one or more video objects onto an optical disc, where each of the one or more video objects includes a video stream, a first audio stream and a second audio stream, the optical disc recording apparatus comprising: an input unit for receiving the video stream and the first audio stream; an audio stream generating unit for generating, based on the received first audio stream, a second audio stream which is used for dubbing; a multiplexing unit for generating the one or more video objects by multiplexing the generated second audio stream, the received video stream, and the received first audio stream into the one or more video objects; and a recording unit for recording the generated one or more video objects onto the optical disc.
With the above construction, the second audio stream for dubbing is multiplexed into the video objects beforehand during the first recording onto the optical disc. As a result, it is possible to generate an optical disc in which video objects facilitating the dubbing are recorded beforehand. It is also possible to record the dubbing audio data together with the original audio data (the first audio stream) since the first and second audio streams are separately recorded.
In the above optical disc recording apparatus, the first audio stream received by the input unit may include packs which each have a fixed size, and the audio stream generating unit includes: a buffer for sequentially storing packs included in the received first audio stream; and a control unit for performing a control so that the packs stored in the buffer are output to be included in the second audio stream.
Also, in the above optical disc recording apparatus, each pack may include a time stamp and a stream identifier, the time stamp specifying a time at which each pack is output from a track buffer of a reproducing apparatus, and the control unit updates time stamps and stream identifiers of the packs stored in the buffer.
With the above construction, it is possible to generate the second audio stream for dubbing by copying each pack of the first audio stream almost as it is. This relieves the optical disc recording apparatus of having an audio encoder for generating the second audio stream for dubbing.
The above optical disc recording apparatus may further comprise: a reading/writing unit for reading a video object from the optical disc; a first buffer unit including a first reading buffer and a first writing buffer, the first reading buffer storing a part of the read video object, and the first writing buffer storing a part of the read video object which is to be written onto the optical disc; a second buffer unit including a second reading buffer and a second writing buffer, the second reading buffer storing a part of the read video object, and the second writing buffer storing a part of the read video object which is to be written onto the optical disc; and a dubbing control unit for performing a control so that while the video object is either read from or written onto the optical disc using one of the first buffer unit and the second buffer unit, the second audio stream in the part of the video object stored in the reading buffer of the other one of the first buffer unit and the second buffer unit is updated, and the part of the video object including the updated second audio stream is stored in the writing buffer of the other buffer unit, where the reading/writing unit sequentially writes the part of the video object in the first writing buffer and the part of the video object in the second writing buffer onto the optical disc, where after the second audio stream has had dubbing performed, the dubbing control unit is capable of restoring the second audio stream to a state before the dubbing by copying the audio data of the first audio stream to the second audio stream.
With the above construction, the dubbing control unit alternately switches the first and second buffer units to read/write the optical disc or to perform the dubbing (update the second audio stream). This achieves the reproduction and dubbing performed in real time. Also, the second audio stream can easily be restored to the original state after dubbing is performed on the second audio stream.
In the above optical disc recording apparatus, the dubbing control unit may instruct the reading/writing unit to read a piece of management information corresponding to the video object read by the reading/writing unit, updates the read piece of management information so that the information indicates that dubbing has been performed on the video object, and instructs the reading/writing unit to write the updated piece of management information onto the optical disc.
With the above construction, it is possible to update the management information so that it indicates that dubbing has been performed on the dubbed video object.
The above object is also fulfilled by an optical disc recording apparatus for recording one or more video objects onto an optical disc, where each of the one or more video objects includes a video stream, the optical disc recording apparatus comprising: an input unit for receiving the video stream; a dubbing stream generating unit for generating a dubbing stream which is used for dubbing; a multiplexing unit for generating the one or more video objects by multiplexing the generated dubbing stream and the received video stream into the one or more video objects; a management information generating unit for generating one or more pieces of management information which respectively correspond to the one or more video objects, each of the one or more pieces of management information indicates whether dubbing has been performed on the dubbing stream in the corresponding video object; and a recording unit for recording the generated one or more video objects and the generated one or more pieces of management information onto the optical disc.
With the above construction, the optical disc recording apparatus multiplexes the dubbing stream into the video objects beforehand during the first recording onto the optical disc. As a result, it is possible to generate an optical disc in which video objects facilitating the dubbing of audio data or sub-picture data are recorded beforehand. Furthermore, it is possible for the recording apparatus and the reproducing apparatus to manage whether the dubbing stream has had dubbing performed by referring to the management information.
The above object is also fulfilled by a method for recording one or more video objects onto an optical disc, the method comprising: an obtaining step for obtaining a video stream and a first audio stream; an audio stream generating step for generating a second audio stream having a bit rate with which audio data corresponding to a reproduction time period of the first audio stream is recorded into the second audio stream; and a recording step for generating the one or more video objects by multiplexing the generated second audio stream, the obtained video stream, and the obtained first audio stream into the one or more video objects and recording the generated one or more video objects onto the optical disc.
With the above construction, the second audio stream for dubbing is multiplexed into the video objects beforehand during the first recording onto the optical disc. As a result, it is possible to generate an optical disc in which video objects facilitating the dubbing are recorded beforehand. It is also possible to record the dubbing audio data together with the original audio data (the first audio stream) since the first and second audio streams are separately recorded.
The above object is also fulfilled by a computer-readable storage medium storing a program for recording one or more video objects onto an optical disc, the program comprising: a program segment for instructing a computer to receive a video stream and a first audio stream; a program segment for instructing the computer to generate a second audio stream having a bit rate with which audio data corresponding to a reproduction time period of the first audio stream is recorded into the second audio stream; a program segment for instructing the computer to generate the one or more video objects by multiplexing the generated second audio stream, the received video stream, and the received first audio stream into the one or more video objects; and a program segment for instructing the computer to record the generated one or more video objects onto the optical disc.
With the above construction, a computer executing the program stored in the storage medium multiplexes the second audio stream for dubbing into the video objects beforehand during the first recording onto the optical disc. As a result, it is possible to generate an optical disc in which video objects facilitating the dubbing are recorded beforehand. It is also possible to record the dubbing audio data together with the original audio data (the first audio stream) since the first and second audio streams are separately recorded.
In the above computer-readable storage medium, the generated second audio stream may have the same audio data as the first audio stream.
Also, in the above computer-readable storage medium, the received first audio stream may include packs which each have a fixed size, and the audio stream generating program segment may instruct the computer to temporarily store packs included in the received first audio stream into a buffer in sequence, and instruct the computer to perform a control so that the packs stored in the buffer are output to be included in the second audio stream.
Also, in the above computer-readable storage medium, each pack may include a time stamp and a stream identifier, the time stamp specifying a time at which each pack is output from a track buffer of a reproducing apparatus, and the audio stream generating program segment instructs the computer to update time stamps and stream identifiers of the packs stored in the buffer.
With the above construction, it is possible for the computer executing the program stored in the storage medium to generate the second audio stream for dubbing by copying each pack of the first audio stream almost as it is.
The above computer-readable storage medium may further comprise: a program segment for instructing the computer to, after the second audio stream has had dubbing performed, restore the second audio stream to a state before the dubbing by copying the audio data of the first audio stream to the second audio stream.
With such a construction, the second audio stream can easily be restored to the original state after dubbing is performed on the second audio stream.
The above object is also fulfilled by an optical disc reproducing apparatus for reproducing an optical disc, where the optical disc includes: a data area in which one or more video objects are recorded, where a video stream, a first audio stream, and a second audio stream are multiplexed into the one or more video objects; and a management area for storing one or more pieces of management information which respectively correspond to the one or more video objects, where the second audio stream has a bit rate with which audio data corresponding to a reproduction time period of the first audio stream is recorded into the second audio stream, where each of the one or more pieces of management information further indicates one of a first state, a second state, a third state, and a fourth state, where the first state indicates that the second audio stream includes the same audio data as the first audio stream, the second state indicates that the second audio stream includes audio data which has been generated from the same source as the first audio stream, the third state indicates that audio data of the second audio stream is irrelevant to audio data of the first audio stream, and the fourth state indicates that the second audio stream has had dubbing performed, the optical disc reproducing apparatus comprising: a reading unit for reading a video object and a piece of management information corresponding to the video object from the optical disc; a reproducing unit for reproducing the video stream and the first audio stream included in the read video object; a control unit for controlling the reproducing unit so that when the piece of management information indicates the fourth state, the reproducing unit is allowed to change reproductions of the first audio stream and the second audio stream in accordance with an instruction to change audio streams input from a user, and that when the piece of management information indicates either of the first state and the second state, the reproducing unit is not allowed to change reproductions of the first audio stream and the second audio stream even when the instruction is input from the user, and the reproducing unit notifies the user that audio streams cannot be changed.
With the above construction, the control unit controls the reproducing unit so that when the optical disc has had dubbing performed (third state), the reproducing unit changes reproductions of the first audio stream and the second audio stream in accordance with an instruction from a user, and that when the dubbing has not been performed on the optical disc (first or second state), it notifies the user that audio streams cannot be changed. That is, the optical disc reproducing apparatus cautions the user that audio streams cannot be changed since dubbing has not been performed yet. The user is notified so for the following reason. If the first audio stream is changed to the second audio stream when the dubbing has not been performed on the optical disc (first or second state), the user may misunderstand the operation thinking that the reproducing apparatus has broken down and failed to change the audio streams since the user will hear the same sound.
The above object is also fulfilled by an optical disc reproducing method for reproducing an optical disc, where the optical disc includes: a data area in which one or more video objects are recorded, where a video stream, a first audio stream, and a second audio stream are multiplexed into the one or more video objects; and a management area for storing one or more pieces of management information which respectively correspond to the one or more video objects, where the second audio stream has a bit rate with which audio data corresponding to a reproduction time period of the first audio stream is recorded into the second audio stream, where each of the one or more pieces of management information further indicates one of a first state, a second state, a third state, and a fourth state, where the first state indicates that the second audio stream includes the same audio data as the first audio stream, the second state indicates that the second audio stream includes audio data which has been generated from the same source as the first audio stream, the third state indicates that audio data of the second audio stream is irrelevant to audio data of the first audio stream, and the fourth state indicates that the second audio stream has had dubbing performed, the optical disc reproducing method comprising: a reading step for reading a video object and a piece of management information corresponding to the video object from the optical disc; a reproducing step for reproducing the video stream and the first audio stream included in the read video object; a control step for, when the piece of management information indicates the fourth state, allowing the reproducing step to change reproductions of the first audio stream and the second audio stream in accordance with an instruction to change audio streams input from a user, and that when the piece of management information indicates either of the first state and the second state, not allowing the reproducing step to change reproductions of the first audio stream and the second audio stream even when the instruction is input from the user, and the reproducing step notifies the user that audio streams cannot be changed.
With the above construction, the optical disc reproducing method cautions the user that audio streams cannot be changed since dubbing has not been performed yet. The user is notified so for the following reason. If the first audio stream is changed to the second audio stream when the dubbing has not been performed on the optical disc (first or second state), the user may misunderstand the operation thinking that the reproducing apparatus has broken down and failed to change the audio streams since the user will hear the same sound.